The <em><u>correct answers</u></em> are:
Supplementary; ∠2 and ∠3; substitution; 2.
Explanation:
Supplementary angles are angles whose measures sum to 180°. Thus this is the first answer.
Since we are told that ∠2 and ∠3 are supplementary, their measures sum to 180° and they are the second answer.
We know that m∠1 + m∠2 = 180° and m∠2 + m∠3 = 180°. We can substitute "m∠2 + m∠3" for 180° in the first equation; this is the substitution property.
To isolate m∠1 on the right, we will subtract m∠2 from each side, and get that m∠1 = m∠3 and the angles are congruent.
To do this make x and y equal 0, y-intercept is at x=0, and x-intercept is at y=0:
x-intercept:
2x+7(0) = -14
2x = -14
x = -7
y-intercept:
2(0) + 7y = -14
7y = -14
y = -2
